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| Titel |
Study of the 2011-2013 unrest at Campi Flegrei caldera (Italy) through InSAR and 3D modelling |
| VerfasserIn |
Elisa Trasatti, Marco Polcari, Christian Bignami, Maurizio Bonafede, Fabrizia Buongiorno, Salvatore Stramondo |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250094020
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| Publikation (Nr.) |
 EGU/EGU2014-9306.pdf |
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| Zusammenfassung |
| Campi Flegrei is a nested caldera in Italy, at the western edge of the Bay of Naples. Together
with Vesuvius and Mt Etna, it is one of the Italian GeoHazard Supersites. The area is
characterized by one of the highest volcanic hazard in the world, due to the very high density
of inhabitants (1800/km2), the persistent activity of the system and the explosive character
of volcanism. A major unrest episode took place in 1982-84, when the town of
Pozzuoli, located at the caldera center, was uplifted by 1.80 m (~1 m/yr). Minor
uplifts of few cm, seismic swarms and degassing episodes took place in 1989, 2000
and 2004-06. Since 2005 Campi Flegrei is uplifting, reaching a ground velocity
of 9 cm/yr in 2012, showing that the caldera is in a critical state on the verge of
instability.
In the present work we consider InSAR time series of the recent activity (2010-2013)
detected by COSMO SkyMed satellite. In particular, the time series show a progressive
velocity increase of ground deformation during 2012, while it slowed down in 2013
approaching zero. The cumulative displacement from COSMO SkyMed descending orbit
(March 2011 – March 2013) show a semicircular pattern centered in Pozzuoli with a
maximum LoS (Line of Sight) displacement of 11 cm and maximum velocity 9 cm/yr
reached along the coastline. The spatial distribution of the cumulative displacement from
COSMO SkyMed ascending orbit show a similar behavior, confirming the bell-shaped
pattern of the deformation at least inside the inner rim of the caldera. The cumulative
ascending LoS displacement between March 2013 - September 2013 is 1-2 cm,
confirming the stall of the unrest after the first few months of 2013 as observed by
GPS.
Initially, several source geometries are adopted (sphere, spheroid, sill) to model the
cumulative deformation between 2011 and 2013. All the sources are located offshore
Pozzuoli at a depth of about 2 km. The sphere and spheroid result to dilate at an annual
volume variation rate of the order of 106 m3/yr. All the models show a general good
agreement with geodetic data but systematic overestimates are found for the enhanced
negative horizontal and vertical deformation across the South-West rim of Campi Flegrei.
This suggests that an additional deformation mechanism may be active in that area.
Numerical models including the structural characteristics of Campi Flegrei are also attempted
in order to model the complete deformation pattern and to better define the source
parameters. A deeper understanding of these characteristics, together with microgravity and
geochemical data, may help to discern between magmatic (e.g., the large uplift episode
during 1982-84, most probably due to deep magmatic source) and hydrothermal
(e.g., mini-uplifts of 2000 and 2004-06 most probably due to pressure variations in
the shallow aquifer) origin of the source responsible of the recent deformation.
Source definition may have important implications in terms of civil protection. |
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